This invention relates in general to apparatus for drilling holes in the earth and dispensing fertilizer into the holes and, more particularly, to such an apparatus having multiple augers and dispensing devices capable of rapidly drilling multiple holes in a selected pattern and dispensing a selected quantity of fertilizer or other plant-aiding material into each hole.
A number of devices and methods of fertilizing plants, in particular trees, in which a hole is drilled in the soil and a quantity of fertilizer or the like is dropped in the hole have been developed and marketed.
Manually operated fertilizer injectors, such as that described by Keyser et al. in U.S. Pat. No. 3,014,443, utilize a hollow rod which is pushed into the ground with the tube closed. Then the tube is opened, such as by withdrawing a plug from within the tube, and a quantity of fertilizer is dropped through the tube into the hole. While simple and inexpensive, such devices are capable of only forming shallow holes and have considerable difficulty with hard ground. Dispensing a reasonably precise amount of fertilizer is difficult and cannot be easily and accurately varied.
Peterson, in U.S. Pat. No. 5,063,863, describes a somewhat more versatile tool for forming a hole and dispensing fertilizer thereinto. A motor-driven auger and a fertilizer container are mounted on a conventional hand-truck carrier. The auger passes through a guide tube above the ground as it drills a hole in the earth. Fertilizer is directed into the guide tube from a side tube connected to the fertilizer container after a hole is drilled and the auger is withdrawn into the guide tube. A rotary measuring device dispenses uniform amounts of fertilizer into each hole. While effective for small scale work, this unit must be manually moved from place to place and can only drill one hole at a time. Further, the measuring device cannot be easily changed to dispense different preselected amounts of fertilizer.
Other manually moved fertilizing apparatus using a powered drilling device and a tube to deliver a quantity of fertilizer into a drilled hole are described by Maier in U.S. Pat. No. 3,695,193 and Gathercoal in U.S. Pat. No. 2,718,856. These devices also require manual movement from place to place and can only drill one hole at a time.
Dion in U.S. Pat. No. 2,109,393 discloses a lawn aerating and fertilizing machine which gangs four powered augers together, all penetrating through a fertilizer bin and funnel shaped guide tubes. The funnels are raised above the ground during drilling and lowered in alignment with drilled holes and the drills are reversed to fill the holes with fertilizer. This assembly can drill and fill shallow holes for fertilizing lawns, but is not effective for fertilizing trees and other large plants, where deep holes each receiving a relatively small quantity of fertilizer are required. Further, while the assembly is being moved from place to place, fertilizer is likely to leak out down the helical drill bits. The amount of fertilizer dispensed can at best be poorly controlled, depending mainly on the depth of the hole. The spacing between drill augers is fixed, so that no adjustment is possible for differing conditions.
A variety of metering devices have been developed for dispensing uniform quantities of powdered or granular materials. Typical of these are the metering systems described by Weitzner in U.S. Pat. No. 3,204,833 and Hafner in U.S. Pat. No. 4,611,731. While the amounts dispensed with each operation of the metering devices are reasonably uniform and consistent, these devices do not include any arrangement for selecting the quantity to be dispensed at different times or under different conditions.
Thus, there is a continuing need for improved apparatus for drilling holes in the earth and dispensing a selected quantity of fertilizer or the like into the holes which can rapidly drill a number of holes while dispensing selected quantities of material into holes spaced selected distances apart. These characteristics are particularly important when fertilizing or treating trees and other large plants, where the hole spacing and fertilizer quantities needed will vary with the size and species of the plant, weather conditions, time of year, etc.